This study plans to examine whether the kinetics of HIV - 1 RNA decay during the initial weeks of antiretroviral therapy differ in the cerebrospinal fluid (CSF) as compared to plasma among antiretroviral-naive patients initiating highly active antiretroviral therapy (HAART). This prospective, open-labeled study will utilize a highly intensive continuous CSF sampling technique: 1. To characterize the relative rate of decline in HIV-1 RNA levels in CSF versus plasma over a 48 hour period during the first week of therapy in patients initiating HAART with the FDA-approved agents nelfinavir (Viracept), stavudine (Zerit, d4t), and lamivudine (Epivir, 3 TC). 2. To assess the range of interpatient variability in early virologic response to HAART in CSF as compared to plasma. 3. Ultimately this approach may be used to compare the relative CNS potencies of various antiretroviral regimes. This may ultimately facilitate rational study to design and clinical decision making.